Oh, there are plenty of other terrible ways:

for _ in mylist:
    break
else:
    # whatever you'd do if mylist was empty

if not any(True for _ in mylist):

try:
    def do_raise(): raise ValueError

    _ = [do_raise() for _ in mylist]
except ValueError:
    pass
else:
    # whatever you'd do i mylist was empty

I could probably come up with a few others as well.

Please note that none of these handles the TypeError if mylist is None.